rbnrpsf HEADAS help file

NAME

rbnrpsf - rebins a radial PSF dataset

USAGE

rbnrpsf infile outfile c_min

DESCRIPTION

rbnrpsf reads an i/p FITS datafile containing a radial point spread function dataset in OGIP-standard format, and rebins the dataset such that such that each new bin contains a user-supplied minimum number of counts. The result is written in the form of a BINTABLE (with extname = OBS RPSF) in the output file (again in OGIP standard format). Details of the o/p file formats supported can be found in the OGIP Calibration Memo CAL/GEN/92-020 available via the OGIP anonymous ftp account on legacy.gsfc.nasa.gov (in Postscript) as caldb/docs/memos/cal_gen_92_020.ps.

The number of ('source') counts in each radial bin is calculated after the subtraction of an appropriate background. By default this background is obtained from the BACKGRND keyword within the i/p file (and may be zero). However users may override this value by entering their own (see below).

WARNINGS ON USAGE

You need to specify the extension number when specifying the name of the input FITS file. If the input filename is infile.fits and the extension for radial profile is 2, then it should be infile.fits[2].

If a radial profile has been background subtracted, with an overestimate for the background rate, negative counts can be present in the input datafile. It is important to note that when PCRPSF performs the rebinning, these negative values are (negatively) included within the summation to determine whether the requested number of minimum counts are in the new bin. This often results in wide output bins.

In order to obtain a good resolution extract the radial profile with many steps, for example, if the extraction is performed from 0 to 10 arcminutes, use at least 80 steps.

PARAMETERS

infile [character string]: The input filename (produced by st2rpsf) containing the 1-dimensional radial profile of a source.
outfile [character string]: The name of the output file to be created (in OGIP standard format), containing an extension with the rebinned radial profile dataset.
c_min [integer]: Minimum number of counts per bin, for rebinning purposes.
bkgd [character string (real value parsed)]: Background count rate (in counts per pixel) should the user wish to override the value written in the BACKGRND keyword in the i/p file. The special/default value ("%") indicates that the value from the i/p data file should be used. The special character "CALC" indicates that the background should be calculated. NOTE: If the background value is changed then the sum of the source counts has to be adjusted (SUMRCTS keyword in datafile).
bkgd_rad [real]: Only prompted for if bkgd="CALC". This is the inner radius for background calculation. NOTE: For Rosat PSPC an inner radius less than 2 arcmins is not recommended as the background estimate could be contaminated by the PSF. For ROSAT HRI data an inner radius less than 1/2 arcmin is not recommended.
chatter [chattiness flag (hidden)]: The value of the chatter flag, useful for reassurance & diagostics purposes. The default value is chatter=10, with chatter <= 5 being very quite and chatter >= 20 very verbose (silly).
(clobber = false) [boolean]: Flag specifying whether or not a pre-existing file with the same name as that requested as the output file from this task will be overwritten.

BUGS

You need to specify the extension number when specifying the name of the input FITS file. For example, if the input filename is infile.fits and the extension for radial profile is 2, then it should be infile.fits[2].

PRIMARY AUTHOR

Rehana Yusaf

HEASARC

NASA/GSFC

http://heasarc.gsfc.nasa.gov/cgi-bin/ftoolshelp